If you don't mind me posting here, I've got two used B3s (One Wifi, one LAN version) for sale in Europe.

They both boot Mouette's most recent Debian Stretch 1.1 image and give the same string about the bootloader (U-Boot 2013.01.01-b3-rodeus-gab59ad7 (Apr 21 2017 - 16:32:01) ), which is an upgraded U-Boot over the old stock one.
One board (named Beta) is slightly damaged though in that its green LED does not work. The other one (Gamma) works without errors.

I have the HDD mounting braces and screws for both of them and one set of sticky thermal pads for an HDD. Also two 12V PSU with a Type C Europlug and one set of Wifi antennae for the wifi case.
One case has some thick shock-absorber feet on it to deal with vibration noise.

Tell me what combination of things you want, and we can agree upon a price. DHL Shipping Europe will be either 9 Euro without tracking or 14 Euro WITH tracking, domestically within Germany is cheaper at 4-6 Euros.

I received an e-mail from Mr. Gates (eBay reseller: netdiskountsdeals (New Jersey, USA)).
His inventory of NOS Excito B3 units is dwindling. He is checking, how many B3s are left —
Some of these B3 servers are not in original boxes (and have NO hard drives).
The UBOOT upgrade, to support 3 TB hard drive, has NOT been applied.

IF interested, contact Mr. Gates via eBay (use his seller name or store) and inform how many you desire.

DO NOT CONTACT ME,
I have no units for sale OR further information (just the messenger, not seller).